A magnitude-8.0 earthquake off the western end of Alaska's
Aleutian Islands shortly before 1 p.m. Monday triggered a tsunami
warning in the area, which was downgraded to a tsunami advisory a couple
of hours later, according to the National Tsunami Warning Center.
A
tsunami warning was in effect for the coastal areas of Alaska from
Nikolski to Attu, including the Pribilof Islands to the north after the
quake hit at 12:53 p.m. The NTWC downgraded the tsunami warning to a
tsunami advisory for the coastal areas of Alaska from Unimak Pass west
to Attu Island at 2:44 p.m. Monday.
The National Tsunami Warning
Center advised people in the warning area to move inland to higher
ground and to avoid the coast until local emergency officials indicated
that it was safe to do so.
According to an updated warning from
the National Tsunami Warning Center at 1:43 p.m., a small tsunami of
just over half a foot was recorded at Amchitka, Alaska.
At 2 p.m.,
Adak reported water leaving the harbor, the National Weather Service's
Anchorage office wrote on Twitter, with residents there moving to higher
ground.
A separate tsunami advisory was initially issued after
the quake, covering Nikolski to Unimak Pass, 80 miles northeast of
Unalaska, according to the National Tsunami Warning Center. "A tsunami
capable of producing strong currents or waves dangerous to persons in or
very near the water is expected," the advisory read. "Currents may be
hazardous to swimmers, boats and coastal structures and may continue for
many hours after the tsunami arrival."
The earthquake hit at
12:53 p.m. Monday at a depth of 62 miles, according to the Alaska
Earthquake Information Center. The earthquake struck 15 miles northwest
of Amchitka, and 29 miles southeast of Little Sitkin Pass. The U.S.
Geological Survey initially listed the earthquake at a magnitude of 7.1,
which was later revised to 8.0.
"The depth of this earthquake will limit the extent of tsunami danger," the updated tsunami warning said.
Natasha
Ruppert, seismologist at the Alaska Earthquake Information Center,
confirmed Monday afternoon that the quake was initially listed at a
magnitude of 7.1 but was then revised to magnitude 8.0 after information
was received from the National Earthquake Information Center.
Aftershocks in the area were occurring Monday afternoon, she said. "We expect there will be quite a few," Ruppert said.
An
aftershock of magnitude 6.0 struck the same area around 1:11 p.m.,
while a magnitude-5.9 quake followed at 1:30, according to the USGS. By 3
p.m., seven earthquakes of magnitude 3.7 or higher had occurred in the
area.